83 CJ7 lacks (Horse) Power....Torque

[83power]

Hello,
This is my first jeep.
1983 CJ7 Laredo
AMC 258 i6 / 4.2l , automatic
2150 MC Carb (new)
31" tires
No Lift
Nutter bypass
HEI Upgrade

I worked on this Jeep for months to get it road worthy and use it as a plow truck.
It idles good, but has very little get up.....I know they have plenty of torque.
In 4x4 and 1st gear, it barely moves my plow when starting out...(6' plow)

Where should I dig in???

 

[Torxhead]

For starters if there is oversize tires on the vehicle, that will change the final drive ratio. Like if you have the not too desired 2.72 axle ratio, that can be a factor.

 

[Peanut Butter]

Does it drive normally without the plow on dry roads? As in enough getup and go. If it does, you vehicle may not be setup to handle the extra weight of a plow. If it does not, I would suspect the Transmission to start with. Rod

 

[Bent]

You probably have the Chrysler TF999 /904 for a 1983 cj. Research the band adjustment procedure for that tranny. also make sure the kick down linkage functions properly on your carb conversion. I don't remember if the Torqueflight transmissions use any vacuum control or not. If it does, make sure it's set up on manifold vacuum. Good luck.

 

[83power]

Hello again,

I do have the TF999 , and I will research the band adjustment. I did adjust the kickdown, twice, but it still lacks power even when driving normally, and loses power going up hill!!
The plow setup is not very heavy, the jeep doesn't even squat when the plow is lifted.

 

[Old Dog]

For starters if there is oversize tires on the vehicle, that will change the final drive ratio. Like if you have the not too desired 2.72 axle ratio, that can be a factor.

Most cj's in that year did come with the 2.72 gears, those coupled with an auto is probably most of your power problems.

 

[Lumpy Grits]

OP-You need to find out what ring & pinion gear ratio you have.
You'll have to remove a diff cover and count the ring and pinion teeth.
LG

 

[Woolyworm]

To save a little work, you can also jack up one side of the rear axle, turn the tire in the air two rotations and count how many revolutions the driveshaft makes for the two tire revolutions. If the DS spins 3 times, you would be 3:1. Not quite as accurate as counting teeth but it gets you in the ball park.


Wooly

 

[83power]

To save a little work, you can also jack up one side of the rear axle, turn the tire in the air two rotations and count how many revolutions the driveshaft makes for the two tire revolutions. If the DS spins 3 times, you would be 3:1. Not quite as accurate as counting teeth but it gets you in the ball park.


Wooly

Ok I will check on the axle ratio and get back as soon as possible.

Also, I am getting the bands adjusted on the tranny.
To cold here to do it myself right now. There is a really good tranny shop in my town, hopefully cheap.

 

[GARGOYLEJEEPER]

Please explain the Nutter Bypass and the HEI Upgrade?

 

[Neuner]

Your rear axle, if still the 20, should have the gear ratio stamped on the back of it for quick reference. Doesn't mean someone didn't go in there and change them but it is easy to check for now. Don't have the coding handy to list here but it will come up in a google search.

The TF999 first gear ratio is 2.74:1 which is why it's not desired among other reasons. Coupled with a high axle gear ratio and large tires and there is your answer. First gear on my T177 is 3.82:1 and the desired T-18 is 6.32:1.

 

[83power]

Please explain the Nutter Bypass and the HEI Upgrade?

Are you asking for yourself or for me?

Nutter Bypass removes all smog controls, if you do a search in this forum you will find a write-up about it.

As for the HEI upgrade, it is a bigger cap, rotor and spacer to handle the larger spark that will happen when you also install the new ignition coil.

You can do a search for this as well on this forum or in Google...tons of info on this.

 

[GARGOYLEJEEPER]

No, I was asking why would you have both?

 

[Tinman22]

The 2.74 1st gear ratio in your 999 is one if not the lowest first gears in an automatic three speed most being in the 2.45/254 range.

As far as strength goes they are not as bad as you might think. Although they do have a few issues none are debilitating in your application.
(Side note the 999/904 is actually a desire able drag racing Transmission due to its low parasitic drag and low 2.74 gear set)

Although 2.72s are common so are 3.31s and 3.54s so visual inspection is a good idea plus you will get to change the gear oil as well. (bonus!)

Question's without the plow,in drive ,can you make it downshift with the throttle?

Also does it up shift properly at different throttle positions? I.e. Hard acceleration longer gear run, lite acceleration shorter gear run.

What is your initial timing set at?

B.t.w comparing crawl ratios between automatics and manuals is silly at best. Try coming to a complete stop without putting the clutch in and see how that works for ya. Torque converters are an amazing piece of engineering and automatic transmissions have given off-roading and rock crawling in particular a level of performance not achievable with a manual Transmission . I Can't remember the last time I saw a 465 four speed in a werock buggy or a 600 hp Coleworx dream for that matter.

And no you can't have my 4 speed!

 

[Old Dog]

No, I was asking why would you have both?

If I'm reading (the "spacer" part) right than he has the nutter and the team rush.??

 

[83power]

If I'm reading (the "spacer" part) right than he has the nutter and the team rush.??

Yes .... you are correct.... The Nutter was done to the Jeep prior to me owning it,
All I did was the Team Rush upgrade..

Regards